Written By Mel Lee-Smith
Published: 09/14/2020Updated: 08/30/2021
Imodium for Dogs | Wag!

Imodium is used to treat diarrhea, gas, and a variety of chronic bowel problems like irritable bowel syndrome and Crohn's disease. While Imodium is available as an over-the-counter medication, you’ll need to consider the dosage, interactions with other medicines, and its effect on different breeds before giving Imodium to your dog. 

You should always consult your veterinarian before administering Imodium. Most complications from Imodium occur due to overdosing, interactions with other drugs, and genetic mutations in certain breeds. Read on for more information about recommended dosage amounts, drug interactions, and considerations.


According to Dr. Klein at the American Kennel Club, the right dosage of Imodium for dogs varies depending on the dog's weight. In general, a dog should take a  2 mg pill for every 40 lbs of body weight. You should administer these pills 2 to 3 times per day.

Imodium pills should be taken orally. If you're struggling to get your dog to take the pill, wrap it in a piece of ham or cheese. Use a small amount of food, as otherwise you risk worsening your dog's digestive issues. It is also possible to get Imodium in liquid form; however, this is much less common as it's harder to measure correctly.


As is the case with most over-the-counter medications, Imodium should not be used as a long-term treatment for your dog's gastrointestinal problems. You shouldn't give your dog Imodium for longer than two days without consulting your veterinarian. 

Imodium takes effect within a couple of hours. If you see no improvement or the issue persists for more than 48 hours, your vet will likely recommend alternatives.


Imodium is an inexpensive drug available over-the-counter. Prices vary from retailer to retailer. A box of 24 Imodium tablets costs $10 to $15 on average.

Side effects

The main active ingredient in all Imodium products is loperamide. Loperamide can cause several side effects, including:

While side effects are generally mild, if you notice any adverse effects, contact your veterinarian. 


Drug interactions

Loperamide is an opiate, which can cause some severe issues when used in conjunction with other medications. If your dog is taking either monoamine oxidase inhibitors or l-deprenyl-based medications, you should avoid giving them Imodium to prevent serious complications. You should also avoid using antihistamines or tranquilizers, as loperamide will drastically increase side effects like drowsiness.

Other drugs that may increase the chances of serious side effects from Imodium include: 

  • Heart medications (quinidine, verapamil, carvedilol, amiodarone, propranolol)

  • Antibiotics (erythromycin, trimethoprim sulfa, sulfamethoxazole)

  • Antifungal medications (ketoconazole, itraconazole)

  • Behavioral medicine (imipramine)

  • Immuno-modulators (cyclosporine)

  • Antiestrogens (tamoxifen)

You should also let your vet know if your dog is taking additional supplements or vitamins, as these may contain active ingredients that can increase the chances of severe side effects. 

Allergic reactions and sensitivity

It is possible for your dog to be allergic to Imodium. If you notice signs of an allergic reaction or other adverse effects, contact your veterinarian immediately. 

Certain dog breeds are known to have a specific genetic mutation which can increase the chances of side effects from Imodium and can even cause neurological toxicity. This mutation (known as MDR-1 or ABCB1) can occur in the following breeds:

A blood test can confirm whether your dog has this genetic mutation. 

Frequently asked questions

What should I do if I forget to give my dog their medication?

You should give your dog the next dose as soon as possible. Never give them two doses at once or very close together. Make sure to wait for the amount of time between dosages as recommended by your veterinarian.

Do I need a prescription for Imodium?

While you can buy Imodium and other loperamide-based products over the counter, dogs are much more sensitive than humans to the effects of this opiate. You should always contact your veterinarian for advice on whether Imodium is suitable for your dog.

Do I need to monitor my dog while giving them Imodium?

You should monitor your dog to ensure the Imodium is working and that there are no adverse side effects. You should make sure you give your dog plenty of water. Your vet may also want to monitor their electrolyte levels and blood pressure.

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